ORSIERES, Switzerland — A Swiss tourist bus plunged into an Alpine ravine near the Great St. Bernard Pass on Sunday, killing 12 people and injuring 15, four of them seriously, police said.

Fourteen people survived because they had been thrown from the bus when it went out of control for still unknown reasons, police in the canton of Valais said.

"We can more or less exclude a skid," said police spokesman Jean-Marie Bornet.

It had been snowing around the Great St. Bernard pass -- a main route through the western Alps near the borders of France and Italy -- but the narrow, winding road was only wet when Sunday's accident occurred, police said.

The bus, which was climbing toward the pass, slammed through a safety barrier and rolled over several times down a steep slope before dropping into the ravine and coming to rest in a stream, La Drance d'Entremont, 800 feet below the road, police spokesman Renato Kalbermatten said.

Worst bus accident in decadesRescuers descended by rope into the ravine and saved a 15th person from the wreckage, but the rest of the bus occupants were killed.

Alain Jacot
/
Keystone via AP

A Swiss tour bus lays on the bank of the Dranse river after an accident on the road to the Great St. Bernard pass between Orsieres and Liddes, western Switzerland, Sunday.

It was the worst bus accident in Switzerland since 1982, when 39 people were killed when a train hit a German tour bus.

Experts will examine the wreckage in an attempt to determine whether there was a technical problem, police said.

Those killed included six women, five men and a 15-year-old boy, investigative magistrate Dominique Lovey told reporters.

Difficult rescueAbout 160 rescuers -- including mountain guides and climbers -- took part in the rescue operation, police said. The use of a helicopter was limited because of fog, but it was able to help rescuers get to the bottom of the ravine.

"The rescue was very difficult," said Bornet. "Getting a person down there is one thing, but the equipment is very heavy."

The bus was based in the Swiss capital, Bern, and was taking passengers to Savona in northwest Italy, where they were to board a Mediterranean cruise ship, bus company manager Heinrich Marti said.

"We bought the bus new only last July," Marti said, telling Swiss television that the driver, who was injured, had called him to report the accident, but was in a state of shock and unable to give details.

There were 24 passengers, two experienced drivers and an attendant on board, Marti said. The bus left its base near Bern at 6 a.m. (0400GMT) and picked up passengers at stops along the way. The accident occurred before 10 a.m. (0800GMT).